The invention relates to an absorbent product such as a sanitary towel, a panty liner or an incontinence pad with a longitudinal direction and a transverse direction, two side edges extending essentially in the longitudinal direction, a front portion, a rear portion, a first surface and a second surface, and an absorption body arranged between the first surface and the second surface. The invention also comprises a method of producing such a product.
Absorbent products of the type referred to in the introduction are in most cases provided with a liquid-blocking rear-side layer, usually a thin liquidtight plastic film layer. An associated problem, however, is that the products feel moist and uncomfortable to wear. The moisture can also cause inconvenience in the form of unpleasant odour and skin irritation. It has therefore become more usual to provide absorbent products with breathable liquid-blocking layers, for example microporous plastic films, or impermeable nonwoven materials. Examples of breathable materials are given in EP 813 848, EP 813 849, EP 710 472, EP 25 315 and U.S. Pat. No. 4,713,069. Such breathable barrier layers do not, however, have an adequate liquid-blocking effect and are therefore in practice used virtually exclusively in panty liners, where the quantity of liquid absorbed is very small. Sanitary towels and incontinence pads, which are expected to absorb considerably greater quantities of liquid, therefore continue to be provided with completely liquidtight barrier layers. There is consequently still a need for improved breathability in absorbent products such as sanitary towels, panty liners and incontinence pads.
Absorbent products such as sanitary towels, panty liners and incontinence pads are intended to be worn in close contact with the body of the wearer. In this connection, such an absorbent product is usually arranged inside the briefs of the wearer and is kept in contact with the body during use by pressure from the briefs. However, it has become much more common for women to wear what are known as thongs, that is to say briefs in which the rear part of the crotch portion is very narrow. In this connection, sanitary towels, panty liners and incontinence pads which are designed to fit in conventional briefs have proved to be virtually impossible to fasten in a thong in such a manner that the towel or the panty liner sits correctly in relation to the body of the wearer and is held in position throughout use. Furthermore, thongs are often worn for aesthetic reasons because they are virtually invisible even under clinging clothes and. do not give rise to unsightly edge lines or creases in the clothes. With a conventional absorbent product, which projects beyond the edges of the thong, a large part of the desired aesthetic effect of wearing a thong is of course lost. Absorbent products have therefore been produced, which are adapted to the shape of a thong. Such absorbent products are described in SE 9803981-1, WO 97/39713 and SE 9901758-4. However, the special essentially triangular shape with a very narrow rear portion, which is necessary in order that a product can fit in a thong, means that the surface area available for absorption is relatively small. The risk of leakage is then great if the product cannot catch and absorb all the bodily fluid discharged.
One object of the invention is therefore to provide a breathable absorbent product with an improved liquid-absorption capacity. Another object of the invention is to provide a breathable absorbent product with a high degree of leakproofness. A further object of the invention is to provide a breathable absorbent product which is suitable for use with a thong.
By means of the present invention, an absorbent product of the type mentioned in the introduction has been produced, which product essentially eliminates the difficulties mentioned above. A product according to the invention is characterized mainly in that the absorption body has a liquid storage area, and a secondary absorption area, the secondary absorption area comprising portions which completely surround the liquid storage area in the plane of the product, the liquid storage area accounting for at least 75% of the total absorption capacity of the product, and a liquid-impermeable material layer being arranged on the second surface of the product and essentially only within the liquid storage area.
By concentrating the absorption capacity in a primary liquid absorption area where liquid can be absorbed and stored, it is possible to limit and control the spread of liquid in the absorbent product. As a result, it is also possible to limit the extent of the liquidtight barrier layer of the product to this area because other parts of the product are expected to absorb only extremely small quantities of liquid.
It is advantageous if the liquid storage area consists essentially of a more fine-capillary and/or more hydrophilic material than the secondary absorption area, or if the liquid storage area comprises superabsorbents, because this means that liquid will be transported in the direction from the secondary absorption area to the liquid storage area and not in the opposite direction. As a result, the edges of the liquid storage area also function as liquid transport barriers, so that liquid will not pass from the liquid storage area to the fluffier and/or less hydrophilic secondary absorption area until the liquid storage area is saturated with liquid.
It has been found that absorbent products worn with thongs stay in place surprisingly well and it is therefore to a great extent possible to predict where wetting and absorption will take place. The present invention exploits this fact to produce a central liquid absorption area with, in relation to the rest of the product, a great absorption capacity and a high degree of leakproofness.
According to one embodiment of the invention, the absorbent product is of essentially triangular plane shape, with a narrower rear portion than front portion. Such a shape makes the product particularly suitable for use together with a thong.
The absorbent product can also be provided with a liquid-permeable rear-side layer which is arranged on the second surface of the product, that is to say the surface intended to face the underwear of the wearer during use of the product. In this connection, the liquid-impermeable material layer is arranged between the liquid storage area of the absorption body and the liquid-permeable rear-side layer. Such a liquid-permeable rear-side layer suitably comprises a nonwoven layer which gives the outside of the product a textile nature. A textile rear side on the product has a number of advantages, such as great comfort, good friction and thus better retention in the underwear, and an attractive appearance.
According to one embodiment of the invention, the, liquid-impermeable material layer is connected to the liquid storage area of the absorption body on that surface of the liquid storage area which is intended to face away from the wearer when the product is in use. Such an embodiment makes it possible to handle the combination of liquid storage material and barrier layer as a single component in a production process.
The liquid storage area should have a great absorption capacity and a good capacity for spreading and storing liquid. In this connection, it is advantageous if the liquid storage area comprises a layer of cellulose fibres with a density of at least 150 g/m3 and preferably a layer suitably of dry-formed cellulose fibres with a density of at least 250 g/m3.
A material which has been found to be suitable for the secondary absorption area comprises a layer of bound cellulose-fibre-based material with a density of at most 125 g/m3 which is arranged on the first surface of the product and extends over the liquid storage area and beyond the edges of the liquid storage area around the entire periphery of the liquid storage area. Alternatively, the secondary absorption material is arranged only around the periphery of the liquid storage area. In this context, a bound material means a material which has been treated with a binder so as to stabilize the fibrous structure in the layer. Accordingly, the material can be bound using latex and/or binding fibres.
According to one embodiment. of the invention, the rear-side material consists of a breathable material with a great capacity to resist liquid penetration.
According to another embodiment, the liquid storage area has an absorption capacity accounting for at least 85% of the total absorption capacity of the product.
The product can also have an adhesive fastening means which is arranged on the rear-side material and allows the passage of gas and water vapour within the area of the secondary absorption area.
The invention also comprises a method of producing an absorbent product according to Patent Claim 1. The method comprises a continuous web of absorbent material being laminated by a first surface to a liquidtight material layer, after which liquid storage areas are clipped or cut from the laminate of absorbent material and liquidtight material, and a continuous web of secondary absorption material being joined to a second surface of the punched-out liquid storage areas so that these are completely surrounded by the secondary absorption material in the plane of the material web, after which absorbent products are clipped or cut from the finished laminate.
According to one embodiment of the invention, a covering of liquid-permeable material is fastened to at least one surface on the laminate of secondary absorption material and liquid storage areas before the absorbent products are cut out of the finished laminate.